I prefer VPI line Axanthics.

As far as Dizzys question goes it seems that while the end results are very similar they are not exactly the same as far as their locations on the gene strand and thus not compatable. So if you breed a Joliff line Axanthic with a VPI line Axanthic you will get a bunch of normal looking axanthics that are double het for both lines. I'm not sure if anyone has bread two double hets together to see if a superior axanthic would come about. It can take years to hit the odds and the end result might not be able to be told from an axanthic of one line so the only way to find out would be breeding it to a pure strain of each. Very rough project if you ask me.